Inkjet Ink Compositions Comprising Polymeric Dispersants Having Attached Chromophore Groups

ABSTRACT

The present invention relates to an inkjet ink composition comprising a liquid vehicle, a pigment, and a polymeric dispersant. In one embodiment, the pigment comprises a colorant having the formula A-(B) x  or is a carbon black pigment and the polymeric dispersant comprises a polymeric group and at least one group having the formula -A′-(B) y (C) z , wherein A and A′ are organic chromophore groups. In a second embodiment, the polymeric dispersant comprises a polymeric group and an organic chromophore group capable of interacting with the pigment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 11/700,413, filed Jan. 31, 2007 and claims the benefit of U.S.Provisional Patent Application No. 60/763,548, filed Jan. 31, 2006. Theentire contents of these applications are incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention, relates to inkjet ink compositions comprising apigment and a polymer dispersant having attached chromophores.

2. Description of the Related Art

An inkjet ink composition generally consists of a vehicle, whichfunctions as a carrier, and a colorant such as a dye or pigment.Additives and/or cosolvents can also be incorporated in order to adjustthe inkjet ink to attain the desired overall performance properties.

In general, pigments alone are not readily dispersible in liquidvehicles, and a variety of techniques have been developed that canprovide stable pigment dispersions useful in applications such as inkjetprinting. For example, dispersants can be added to the pigment toimprove its dispersibility in a particular medium. Examples ofdispersants include water-soluble polymers and surfactants. A widevariety of polymers have been used as dispersants, and these are oftentailored to the type of pigment to be dispersed. Typically, polymericdispersants have a molecular weight, less than 20,000 in order tomaintain solubility and to provide pigment stability. For example, JP10-130554 describes inkjet ink compositions comprising substitutedquinolonoquinolones which further comprise a rosin, resin, surfactant,or dispersant, such as a three-component copolymer composed of methylmethacrylate, ethyl acrylate, and methacrylic acid.

Non-polymeric materials can also be used as dispersants for inkjet inks.For example, U.S. Pat. No. 5,750,323 describes a solid particle aqueousdispersion of a colorant dispersed using a relatively small amount of acompound that is structurally similar to the colorant. This structurallysimilar additive is structurally distinct from the colorant and containsan identical structural section making up at least 75% of the totalmolecular weight of the colorant. The additive has at least onesubstitutent bonded to the identical structural section that has amolecular weight higher than the corresponding substituent of thecolorant. However, such additives are described for non-pigmentcolorants (i.e., filter dyes).

In addition, U.S. Pat. No. 5,716,435 describes a water-dispersed inkjetrecording liquid prepared by a salt-milling method in which a mixturecontaining an organic pigment, a water-soluble inorganic salt, and awater-soluble solvent is mechanically kneaded. A pigment derivative,which is a substituted derivative of a pigment residue or heterocyclicring residue, or a resin, which is a polymeric dispersant, may also beincluded. However, such a composition requires the use of both thepigment derivative and polymeric dispersants as separate additives, eachof which may be affected by other components in the inkjet inkcomposition.

Dispersants having pigment derivatives attached to a polymeric grouphave also been described. For example, GB 2036779 describes polyetherdisazo dyestuffs having specified formulas which includes a disazo dyeand an attached polyalkylene oxide group. These dyestuffs are useful fordying and printing synthetic fibers. Also, JP 63-175080, JP 06-065521,JP 07-041689, and JP 2993088d each describe pigment compositionscomprising a pigment and a polymer having an attached quinacridonederivative, which can be used for dispersing a pigment for coatings orvarnishes. However, none of these references teaches the use of suchadditives for the demanding requirements of inkjet ink compositions.

Methods for the preparation of modified pigment products have also beendeveloped which can provide a pigment with a variety of differentattached functional groups. For example, U.S. Pat. No. 5,851,280discloses methods for the attachment of organic groups onto pigmentsincluding, for example, attachment via a diazonium reaction wherein theorganic group is part of the diazonium salt. Other methods to preparemodified pigments, including those having attached polymeric groups,have also been described. For example, PCT Publication No. WO 01/51566discloses methods of making a modified pigment by reacting a firstchemical group and a second chemical group to form a pigment havingattached a third chemical group. These methods provide modified pigmentshaving attached groups and pigment compositions, including inkjet inkcompositions, with improved overall performance properties that do notrequire the addition of dispersant. However, a pigment modification stepis needed.

As the inkjet printing industry moves towards print performance similarto that of laser printing, there remains a need for inkjet inkcompositions comprising pigments and a dispersant having improvedproperties, such as improved stability, thereby providing alternativesto modified pigment dispersions.

SUMMARY OF THE INVENTION

The present invention relates to an inkjet ink composition comprising:a) a liquid vehicle, b) a pigment, and c) a polymeric dispersant. In oneembodiment of the invention, the pigment comprises a colorant having theformula A-(B)_(x) or is a carbon black pigment, and the polymericdispersant comprises a polymeric group and at least one group having theformula -A′-(B)_(y)(C)_(z), wherein A and A′ are organic chromophoregroups; B, which can be the same or different when x or y>1, is asubstituent on A or A′; C, which can be the same or different when z>1,is a substituent on A′ and is different than B; x, y, and z are 0, 1, 2,3, or 4 with y being less than or equal to x. In a second embodiment,the pigment comprises a colorant having the formula A-(B)_(x), whereinA, B, and x are as described above, and the polymeric dispersantcomprises a polymeric group and an organic chromophore group capable ofinteracting with the pigment.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the presentinvention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to inkjet ink compositions and dispersionscomprising a vehicle, a pigment, and a dispersant.

The vehicle of the inkjet ink composition of the present invention is aliquid vehicle and may be either a non-aqueous vehicle or an aqueousvehicle. Preferably, the vehicle is an aqueous vehicle, which is avehicle that contains greater than 50% water. For example, the aqueousvehicle can be water or mixtures of water with water miscible solventssuch as alcohols. Preferably the aqueous vehicle is water, and theinkjet ink composition is an aqueous inkjet ink composition.

The pigment of the inkjet ink composition of the present invention canbe any type of pigment conventionally used by those skilled in the art.For example, the pigment may be a black pigment, including variouscarbonaceous pigments. Preferred black pigments include carbon blacks(Pigment Black 7) such as channel blacks, furnace blacks and lampblacks.

The pigment may also be an organic colored pigment, including a blue, ablack, a brown, a cyan, a green, a white, a violet, a magenta, a red, anorange, or a yellow organic pigment. Mixtures of different pigments canalso be used. Organic colored pigments comprise colorants and can beclassified by their colorant type. Suitable colorant classes for thecolored pigments useful in the inkjet ink compositions of the presentinvention include, for example, anthraquinones, phthalocyanine blues,phthalocyanine greens, disazos, monoazos, pyranthrones, perylenes,heterocyclic yellows, quinolonoquinolones, isoindolones, indanthrones,quinacridones, and (thio)indigoids. Such pigments are commerciallyavailable in either powder or press cake form from a number of sourcesincluding, BASF Corporation, Engelhard Corporation and Sun ChemicalCorporation. Examples of other suitable colored pigments are describedin the Colour Index, 3rd edition (The Society of Dyers and Colourists,1982).

Preferably, the organic colored pigment used in the inkjet inkcompositions of the present invention is a yellow, magenta, or cyanpigment. Examples of preferred yellow pigments include those comprisingquinolonoquinolone colorants, azo colorants, or isoindolone colorants.Examples of preferred magenta pigments include those comprisingquinacridone colorants. Examples of preferred cyan pigments includethose comprising phthalocyanine or indanthrone colorants.

The colorant of an organic colored pigment comprises an organicchromophore group, which may be further substituted with varioussubstituents. As used herein, the term “organic chromophore group” isthat portion of the chemical structure of the colorant that provides theessential color of the colorant. The term “substituent” is a group,particularly a functional group, bonded to the chromophore that furtherdefines the specific color and hue of the colorant and differentiates itfrom other pigments in the same colorant class. Thus, the organicchromophore group is that portion of the colorant structure to which thesubstituents are bonded and would be considered to be the backbone orskeleton structure of the colorant.

For example, one class of yellow pigments comprises a quinolonoquinolonecolorant. Examples of this type of pigment are Pigment Yellow 218,Pigment Yellow 220, and Pigment Yellow 221, which are shown below:

For this class of pigments, the organic chromophore group of thecolorant would be a quinolonoquinolonyl group and the substituents wouldbe halogen groups. In a similar way, Pigment Violet 19, Pigment Red 122,and Pigment Red 202 each comprise a quinacridone colorant as follows:

Thus, for this class of pigments, the organic chromophore group of thecolorant would be the quinacridonyl group. For Pigment Red 122, thereare two methyl group substituents and for Pigment Red 202, there are twochlorine group substituents. For Pigment Violet 19, there are nosubstituents, and the colorant is the organic chromophore.

In the inkjet ink compositions of the present invention, the pigment maycomprise a colorant having the formula A-(B)_(x). A is an organicchromophore group and B is a substituent on A, as defined above. Thenumber of substituents is represented by x and can be any value from 0to the total number of available sites on the organic chromophore group,depending on the specific colorant class. Preferably x has a value of 0,I, 2, 3, or 4, although higher levels of substitution may also bepossible. When x is greater than or equal to one (i.e, A has more thanone substituent), each B can be the same or different. Thus, preferably,A has up to 4 various types of substituents or can have up to 4 of thesame substituent.

For example, the pigment can be a yellow pigment comprising aquinolonoquinolone colorant having the formula A-(B)_(x), wherein A is aquinolonoquinolonyl group, B is a substituent on A, and x represents thenumber of substituents, B. The colorant can be either a symmetrical orunsymmetrical quinolonoquinolone colorant and can include those in whichB is a halogen group, a methoxy group, or an alkyl group (such as amethyl or ethyl group). For this example, x is preferably 1 or 2. Thus,specific examples of preferred quinolonoquinolone colorants are2,6-difluorquinolonoquinolone as well as the 3-fluoro-, 2-fluoro-, or3-chloro-quinolonoquinolone colorants shown above.

As another example, the pigment can be a yellow pigment comprising anazo colorant having the formula A-(B)_(x), wherein A is a2-(phenylazo)-N-(phenyl)-3-oxobutanamidyl group, B is a substituent onA, and x represents the number of substituents, B. Examples of B includealkoxy groups, especially methoxy groups, and nitro groups. For example,the pigment may be Pigment Yellow 74, which comprises a2-((2-methoxy-4-nitrophenyl)azo)-N-(2-methoxyphenyl)-3-oxobutanamidecolorant. For this colorant, the organic chromophore group A is asdescribed above and has 3 substituents B—two methoxy groups and onenitro group. Thus, x is 3. Other azo colorants will be known to oneskilled in the art.

As additional examples, the pigment can be a cyan pigment comprising aphthalocyanine colorant having the formula A-(B)_(x), wherein A is aphthalocyaninyl group, such as a copper phthalocyaninyl group. Also, thepigment can be a magenta pigment comprising a, quinacridone coloranthaving the formula A-(B)_(x), wherein A is a quinacridonyl group.

The pigment can have a wide range of BET surface areas, as measured bynitrogen adsorption, depending on the desired properties of the pigment.As known to those skilled in the art, a higher the surface area willcorrespond to smaller particle size. If a higher surface area is notreadily available for the desired application, it is also wellrecognized by those skilled in the art that the pigment may be subjectedto conventional size reduction or comminution techniques, such as ballor jet milling, to reduce the pigment to a smaller particle size, ifdesired.

The inkjet ink composition of the present invention further comprises apolymeric dispersant, which is a dispersant comprising a polymericgroup. The polymeric group may be any of those known in the art capableof providing a stable pigment dispersion in a liquid vehicle and,preferably, in an aqueous vehicle. For example, the polymeric group maybe an anionic, cationic, or nonionic homopolymeric or copolymeric groupand can include any group derived from the additional polymericdispersants described below that can be used in the inkjet inkcompositions of the present invention. Specific examples of polymericgroups include polyvinyl alcohol groups, polyvinylpyrrolidone groups,polyurethane groups, acrylate or methacrylate polymeric groups (such ashomopolymeric or copolymeric groups prepared from methacrylic acid,acrylic acid, or esters thereof), polystyrene-acrylate) orpoly(styrene-methacrylate) groups (such as copolymeric groups preparedfrom styrene and methacrylic acid, acrylic acid, or esters thereof),polymeric groups prepared from styrene and maleic acid or maleicanhydride, polymer groups prepared from vinyl acetate (such as vinylacetate-ethylene copolymeric groups, vinyl acetate-fatty acid vinylethylene copolymer groups, vinyl acetate-maleate ester copolymer groups,vinyl acetate-crotonic acid copolymer groups, and vinyl acetate-acrylicacid copolymer groups), and salts thereof. Preferably the polymericgroup comprises at least one acid group or salt thereof or anhydridegroup, such as a methacrylate or acrylate polymeric group or a maleicacid or maleic anhydride polymeric group, a polyurethane group, astyrene-acrylic acid polymeric group, a styrene-methacrylic acidpolymeric group, or salts thereof. Suitable salts include inorganic ororganic counterions such as Na⁺, K⁺, Li⁺, NH₄ ⁺, NR′₄ ⁺, where R′, whichcan be the same or different, represents hydrogen or an organic groupsuch as a substituted or unsubstituted aryl and/or alkyl group.

The polymeric group has a molecular weight suitable for the material tofunction as a dispersant. Typically, the molecular weight of thepolymeric group is greater than about 500 and less than about 500,000.Preferred are polymeric groups having a molecular weight from about1,000 to 100,000, more preferably from about 5,000 to about 80,000, andmost preferably from about 10,000 to about 50,000.

In one embodiment of the inkjet ink composition of the presentinvention, the polymer dispersant further comprises at least one grouphaving the formula -A′-(B)_(y)(C)_(z). A′ is an organic chromophoregroup and can be any of those described above in relationship to thecolorant of the pigment used in the inkjet ink composition of thepresent invention. B and C are substituents on A′, and y and z representthe number of substituents B and C respectively. The value of y and zcan be from 0 to the total number of available sites on the organicchromophore group and is preferably 0, 1, 2, 3, or 4. When y and/or zare greater than 1, each B substituent can be the same or different andeach C substituent can be the same or different. Substituents B and Ccan be any of those described above regarding the substituent B of thecolorant of the pigment used in the inkjet ink composition of thepresent invention. However, for the polymeric dispersant, B and C aredifferent.

For this embodiment, preferably, the organic chromophore group isattached to the polymeric group of the polymeric dispersant through alinking group. Thus, the polymeric dispersant may comprise a grouphaving the formula -LG-A′(B)_(y)(C)_(z), wherein LG is a linking group,which is a group through which the organic chromophore group, A′, isbonded to the polymeric group. Thus, LG may be attached directly to thepolymeric group or may be attached to a group that is attached to thepolymeric group. LG can be a bond or can be a chemical group that isformed by the reaction of a functional group of the polymeric group,with a reactive group of the organic chromophore group, A′, forming, forexample, a group such as an ester group, an amide group, an ether group,or the like. For example, if polymeric group is formed from methacrylicacid or acrylic acid, the linking group, LG, may be formed by thereaction of the acid functional group of the polymeric group with anucleophilic reactive group of the organic chromophore group, A′. In asimilar way, LG may be formed by the reaction of an anhydride group ofthe polymeric group and a nucleophilic, group of A′. Also as an example,if the polymeric group has a nucleophilic end group, such as an alcoholor amine, the linking group, LG, may be formed by the reaction of thisfunctional group with an electrophilic reactive group of the organicchromophore group, A′. Other combinations of the functional groups ofthe polymeric group and reactive groups of A′ can be used.

As a particular example, LG may comprise a group having the formula—X-ALK1-, wherein X is O, NR, or S and ALK is an alkylene group, anarylene group, an aralkylene group, or an alkarylene group having 1-18carbon atoms, including, for example, a C1-C6 alkylene group. In thisformula, R is hydrogen, a C1-C6 alkyl group, or an aryl group.Preferably, the polymeric dispersant comprises at least one group havingthe formula —X-ALK1-A′-(B)_(y)(C)_(z), wherein A′, B, C, y, and z are asdescribed above. More preferably, X is NH and ALK1 is CH₂.

The polymeric dispersant may further comprise attached pendant groups inaddition to the organic chromophore group. Such groups may be used tooptimize the properties of the polymeric dispersant, such as by changingits hydrophobicity/hydrophilicity. For example, if the polymeric groupcomprises anhydride groups, some of them may be reacted with anucleophilic group of A′, such as an amine group, forming a group havingthe formula X-ALK1-A′-(B)_(y)(C)_(z) described above. Remaininganhydride groups may be further reacted with other nucleophiliccomponents, such as amines and alcohols, forming attached pendantgroups. Thus, the polymeric dispersant may further comprise at least onependant group having the formula —X-ALK2, wherein X, as described above,is O, NR, or S and R is hydrogen, a C1-C6 alkyl group, or an aryl group,and ALK2 is an alkyl group, an aryl group, an aralkyl group, or analkaryl group having 1-18 carbons. Preferably the pendant group has theformula —X-ALK2, and more preferably, X is NH.

As an example of this embodiment, the pigment can comprise a coloranthaving the formula A-(B)_(x), as described above. Thus, in this example,the polymeric dispersant and the colorant of the pigment both compriseorganic chromophore groups. This group may be the same organicchromophore or may be different—A and A′ may be the same or different.As particular examples, the organic chromophore group of the colorantmay be a quinolonoquinolonyl group and the organic chromophore group ofthe polymeric dispersant may a quinolonoquinolonylene group—i.e., bothorganic chromophore groups may be a quinolonoquinolone chromophoregroup. Also, the organic chromophore group of the colorant may be a2-(phenylazo)-N-(phenyl)-3-oxobutanamidyl group and the organicchromophore group of the polymeric dispersant may be a2-(phenyleneazo)-N-(phenylene)-3-oxobutanamide group, both being thesame azo chromophore. In addition, both A and A′ may be phthalocyaninegroups (A being a phthalocyaninyl group and A′ being a phthalcyaninylenegroup) or may both be quinacridone groups (A being a quinacridonyl groupand A′ being a quinacridonylene group). Alternatively, the organicchromophore groups of the colorant and the polymeric dispersant may bedifferent from each other. For example, the organic chromophore group ofthe colorant may be a phthalocyaninyl group and the organic chromophoregroup of the polymeric dispersant may be a quinacryidonylene group.Other mixed combinations of pigment colorant and polymeric dispersantorganic chromophore groups are also possible.

When A and A′ are the same, the substituents on each can be the same ordifferent. For example, if the organic chromophore group of both thecolorant and the polymeric dispersant have the same type and number ofsubstituents, then x equals y, and z is 0. If neither have attachedsubstituents, then both y and z are 0 and the organic chromophore groupof both the polymeric dispersant and the colorant is the same as thecolorant itself. Also, the substituents bonded to the organicchromophore groups of the colorant and the polymeric dispersant candiffer, either in number, type, or both. For example, the organicchromophore group of the polymeric group may comprise the same types ofsubstituents as the organic chromophore group of the colorant, but fewerof them. In this case, y is less than x, and z is 0. Also, the organicchromophore group of the polymeric group may comprise differentsubstituents than the organic chromophore group of the polymer group. Inthis case, y is 0 and z is 1, 2, or 3. Furthermore, the organicchromophore group of the polymeric dispersant may comprise some of thesame substituents as the organic chromophore group of the colorant, butfewer of them, as well as at least one additional substituent. In thiscase, y is less than x and z is 1, 2, or 3.

As another example of this embodiment, the pigment can be a carbon blackpigment. Any of those described above may be used. Thus, in thisexample, the pigment is a carbon black pigment and the polymericdispersant comprises a polymeric group and an organic chromophore grouphaving the formula described above. As a specific example, the organicchromophore group is either a quinacridonylene group or a2-(phenyleneazo)-N-(phenylene)-3-oxobutanamide group and the pigment iscarbon black. The carbon black pigment can have a wide range of BETsurface areas, as measured by nitrogen adsorption, depending on thedesired properties of the pigment. Preferably, the pigments have a BETsurface area between about 10 m²/g and about 1500 m²/g, more preferablybetween about 20 m²/g and about 600 m²/g. Also, the carbon black pigmentcan have a wide variety of primary particle sizes known in the art. Forexample, the pigment may be a carbon black having a primary particlesize of between about 5 nm to about 100 nm, including about 10 nm toabout 80 nm and 15 nm to about 50 nm. In addition, the carbon blackpigment can also have a wide range of dibutylphthalate absorption (DBP)values, which is a measure of the structure or branching of the pigment.For example, the pigment may be a carbon black having a DBP value offrom about 25 to 400 mL/100 g, including from about 30 to 200 mL/100 gand from about 50 to 150 mL/100 g.

In another embodiment of the inkjet ink composition of the presentinvention, the polymeric dispersant comprises at least one organicchromophore group that is capable of interacting with the pigment usedin the inkjet ink composition. For this embodiment, any of the pigmentsdescribed above may be used. However, it is preferred that the pigmentcomprises a colorant having the formula A-(B)_(x), wherein A, B, and xare as described above. Thus, the polymeric dispersant comprises atleast one organic chromophore group capable of interacting with thecolorant of the pigment.

Preferably, the interacting organic chromophore group is attached to thepolymeric group of the polymeric dispersant through a linking group,including any of those described above. For example, the polymericdispersant may have the formula -LG-Q, wherein LG is a linking group andQ is the organic chromophore group that is capable of interacting withthe pigment used in the inkjet ink composition. Q can be any of theorganic chromophore groups described above for A and A′, as long as thegroup interacts with the pigment. It is preferred that the interactionbetween Q and the pigment is strong and therefore preferred types ofinteractions would include hydrogen bonding and pi-pi stacking. Also, Qmay co-crystallize with the pigment, such as by intercalating into thecrystal structure through any of the various mechanisms known in theart. Strong interaction between Q of the polymeric dispersant with thepigment, including with the colorant of the pigment, has surprisinglybeen found to form stable dispersions of the pigment that are alsothermally stable and can be printed by an inkjet ink printing process toform images having good overall properties.

As stated previously, the aqueous inkjet ink compositions of the presentinvention comprises an aqueous vehicle, a pigment, and a polymericdispersant. Each of these is present in an amount effective to providedesirable image quality (for example, optical density) withoutdetrimentally affecting the performance of the inkjet ink. For example,typically, the pigment will be present in an amount ranging from about0.1% to about 20%, based, on the weight of the inkjet ink composition.The amount of the polymeric dispersant can vary depending on suchfactors as molecular weight and polymer composition. Typically, thepolymeric dispersant is used at levels from about 0.5 to about 15 partsrelative to 100 parts pigment. Levels outside of this range typicallyproduce inkjet inks with poor dispersion properties, such as largepigment particle sizes. For example, the particle size of the pigment inthe inkjet ink composition of the present invention are generally about200 nm or less.

The inkjet ink compositions of the present invention can be formed witha minimum of additional components (additives and/or cosolvents) andprocessing steps. However, suitable additives may also be incorporatedinto these inkjet ink compositions to impart a number of desiredproperties while maintaining the stability of the compositions. Forexample, surfactants (non-polymeric dispersants) may be added to furtherenhance the colloidal stability of the composition. Other additives arewell known in the art and include humectants, biocides, binders, dryingaccelerators, penetrants, and the like. The amount of a particularadditive will vary depending on a variety of factors but are generallypresent in an amount, ranging between 0% and 40% based on the weight ofthe inkjet ink composition. In addition,, the inkjet ink compositionsmay contain organic chromophores which correspond to the organicchromophore group of the polymeric dispersant but which are not attachedto the polymeric dispersant, which may result from the preparation ofthe dispersant. Other organic chromophores may also be used

Additional dispersing agents (surfactants and/or polymeric dispersantsthat differ from those described above) may be added to further enhancethe colloidal stability of the composition or to change the interactionof the ink with either the printing substrate, such as printing paper,or with the ink printhead. Various anionic, cationic and nonionicdispersing agents can be used in conjunction with the ink composition ofthe present invention, and these may be in solid form or as a watersolution.

Representative examples of anionic dispersants or surfactants include,but are not limited to, higher fatty acid salts, higheralkyldicarboxylates, sulfuric acid ester salts of higher alcohols,higher alkyl-sulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, naphthalene sulfonates (Na, K, Li, Ca, etc.), formalinpolycondensates, condensates between higher fatty acids and amino acids,dialkylsulfosuccinic acid ester salts, alkylsulfosuccinates,naphthenates, alkylether carboxylates, acylated peptides, α-olefinsulfonates, N-acrylmethyl taurine, alkylether sulfonates, secondaryhigher alcohol ethoxysulfates, polyoxyethylene alkylphenylethersulfates, monoglycylsulfates, alkylether phosphates and alkylphosphates. For example, polymers and copolymers of styrene sulfonatesalts, unsubstituted and substituted naphthalene sulfonate salts (e.g.alkyl or alkoxy substituted naphthalene derivatives), aldehydederivatives (such as unsubstituted alkyl aldehyde derivatives includingformaldehyde, acetaldehyde, propylaldehyde, and the like), maleic acidsalts, and mixtures thereof may be used as the anionic dispersing aids.Salts include, for example, Na⁺, Li⁺, K⁺, Cs⁺, Rb⁺, and substituted andunsubstituted ammonium cations. Representative examples of cationicsurfactants include aliphatic amines, quaternary ammonium salts,sulfonium salts, phosphonium salts and the like.

Representative examples of nonionic dispersants or surfactants that canbe used in ink jet inks of the present invention include fluorinederivatives, silicone derivatives, acrylic acid copolymers,polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether,polyoxyethylene secondary alcohol ether, polyoxyethylene styrol ether,polyoxyethylene lanolin derivatives, ethylene oxide derivatives ofalkylphenol formalin condensates, polyoxyethylene polyoxypropylene blockpolymers, fatty acid esters of polyoxyethylene polyoxypropylenealkylether polyoxyethylene compounds, ethylene glycol fatty acid estersof polyethylene oxide condensation type, fatty acid monoglycerides,fatty acid esters of polyglycerol, fatty acid esters of propyleneglycol, cane sugar fatty acid esters, fatty acid alkanol amides,polyoxyethylene fatty acid amides and polyoxyethylene alkylamine oxides.For example, ethoxylated monoalkyl or dialkyl phenols may be used. Thesenonionic surfactants or dispersants can be used alone or in combinationwith the aforementioned anionic and cationic dispersants.

The dispersing agents may also be a natural polymer or a syntheticpolymer dispersant. Specific examples of natural polymer dispersantsinclude proteins such as glue, gelatin, casein and albumin; naturalrubbers such as gum arabic and tragacanth gum; glucosides such assaponin; alginic acid, and alginic acid derivatives such aspropyleneglycol alginate, triethanolamine alginate, and ammoniumalginate; and cellulose derivatives such as methyl cellulose,carboxymethyl cellulose, hydroxyethyl cellulose and ethylhydroxycellulose. Specific examples of polymeric dispersants, includingsynthetic polymeric dispersants, include polyvinyl alcohols;polyvinylpyrrolidones; acrylic or methacrylic resins (often written as“(meth)acrylic”) such as poly(meth)acrylic acid, acrylicacid-(meth)acrylonitrile copolymers, potassium(meth)acrylate-(meth)acrylonitrile copolymers, vinylacetate-(metha)acrylate ester copolymers and (meth)acrylicacid-(meth)acrylate ester copolymers; styrene-acrylic or methacrylicresins such as styrene-(meth)acrylic acid copolymers,styrene-(meth)acrylic acid-(meth)acrylate ester copolymers,styrene-α-methylstyrene-(meth)acrylic acid copolymers,styrene-α-methylstyrene-(meth)acrylic acid-(meth)acrylate estercopolymers; styrene-maleic acid copolymers; styrene-maleic anhydridecopolymers, vinyl naphthalene-acrylic or methacrylic acid copolymers;vinyl naphthalene-maleic acid copolymers; and vinyl acetate copolymerssuch as vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinylethylene copolymers, vinyl acetate-maleate ester copolymers, vinylacetate-crotonic acid copolymer and vinyl acetate-acrylic acidcopolymer; and salts thereof.

Humectants and water soluble organic compounds may also be added to theinkjet ink composition of the present invention, particularly for thepurpose of preventing clogging of the nozzle as well as for providingpaper penetration (penetrants), improved drying (drying accelerators),and anti-cockling properties. Specific examples of humectants and otherwater soluble compounds that may be used include low molecular-weightglycols such as ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol and dipropylene glycol; diols containing from about2 to about 40 carbon atoms, such as 1,3-pentanediol, 1,4-butanediol,1,5-pentanediol, 1,4-pentanediol, 1,6-hexanediol, 1,5-hexanediol,2,6-hexanediol, neopentylglycol(2,2-dimethyl-1,3-propanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,2,6-hexanetriol, poly(ethylene-co-propylene)glycol, and the like, aswell as their reaction products with alkylene oxides, including ethyleneoxides, including ethylene oxide and propylene oxide; triol derivativescontaining from about 3 to about 40 carbon atoms, including glycerine,trimethylpropane, 1,3,5-pentanetriol, 1,2,6-hexanetriol, and the like aswell as their reaction products with alkylene oxides, including ethyleneoxide, propylene oxide, and mixtures thereof; neopentylglycol,(2,2-dimethyl-1,3-propanediol), and the like, as well as their reactionproducts with alkylene oxides, including ethylene oxide and propyleneoxide in any desirable molar ratio to form materials with a wide rangeof molecular weights; thiodiglycol; pentaerythritol and lower alcoholssuch as ethanol, propanol, iso-propyl alcohol, n-butyl alcohol,sec-butyl alcohol, and tert-butyl alcohol, 2-propyn-1-ol(propargylalcohol), 2-buten-1-ol, 3-buten-2-ol, 3-butyn-2-ol, and cylcopropanol;amides such as dimethyl formaldehyde and dimethyl acetamide; ketones orketoalcohols such as acetone and diacetone alcohol; ethers such astetrahydrofurane and dioxane; cellosolves such as ethylene glycolmonomethyl ether and ethylene glycol monoethyl ether, triethylene glycolmonomethyl (or monoethyl) ether; carbitols such as diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, and diethyleneglycol monobutyl ether; lactams such as 2-pyrrolidone,N-methyl-2-pyrrolidone and ε-caprolactam; urea and urea derivatives;inner salts such as betaine, and the like; thio (sulfur) derivatives ofthe aforementioned materials including 1-butanethiol; t-butanethiol1-methyl-1-propanethiol, 2-methyl-1-propanethiol;2-methyl-2-propanethiol; thiocyclopropanol, thioethyleneglycol,thiodiethyleneglycol, trithio- or dithio-diethyleneglycol, and the like;hydroxyamide derivatives, including acetylethanolamine,acetylpropanolamine, propylcarboxyethanolamine, propylcarboxypropanolamine, and the like; reaction products of the aforementionedmaterials with alkylene oxides; and mixtures thereof. Additionalexamples include saccharides such as maltitol, sorbitol, gluconolactoneand maltose; polyhydric alcohols such as trimethylol propane andtrimethylol ethane; N-methyl-2- pyrrolidene;1,3-dimethyl-2-imidazolidinone; sulfoxide derivatives containing fromabout 2 to about 40 carbon atoms, including dialkylsulfides (symmetricand asymmetric sulfoxides) such as dimethylsulfoxide,methylethylsulfoxide, alkylphenyl sulfoxides, and the like; and sulfonederivatives (symmetric and asymmetric sulfones) containing from about 2to about 40 carbon atoms, such as dimethylsulfone, methylethylsulfone,sulfolane (tetramethylenesulfone, a cyclic sulfone), dialkyl sulfones,alkyl phenyl sulfones, dimethylsulfone, methylethylsulfone,diethylsulfone, ethylpropylsulfone, methyiphenylsulfone,methylsulfolane, dimethylsulfolane, and the like. Such materials may beused alone or in combination.

Biocides and/or fungicides may also be added to the inkjet inkcomposition of the present invention. Biocides are important inpreventing bacterial growth since bacteria are often larger than inknozzles and can cause clogging as well as other printing problems.Examples of useful biocides include, but are not limited to, benzoate orsorbate salts, and isothiazolinones.

Various polymeric binders can also be used in conjunction with theinkjet ink composition of the present invention to adjust the viscosityof the composition as well as to provide other desirable properties.Suitable polymeric binders include, but are not limited to, watersoluble polymers and copolymers such as gum arabic, polyacrylate salts,polymethacrylate salts, polyvinyl alcohols, hydroxypropylenecellulose,hydroxyethylcellulose, polyvinylpyrrolidinone, polyvinylether, starch,polysaccharides, polyethyleneimines with or without being derivatizedwith ethylene oxide and propylene oxide; and the like. Additionalexamples of water-soluble polymer compounds include various dispersantsor surfactants described above, including, for example, styrene-acrylicacid copolymers, styrene-acrylic acid-alkyl acrylate terpolymers,styrene-methacrylic acid copolymers, styrene-maleic acid copolymers,styrene-maleic acid-alkyl acrylate terpolymers, styrene-methacrylicacid-alkyl acrylate terpolymers, styrene-maleic acid half estercopolymers, vinyl naphthalene-acrylic acid copolymers, alginic acid,polyacrylic acids or their salts and their derivatives. In addition, thebinder may be added or present in dispersion or latex form. For example,the polymeric binder may be a latex of acrylate or methacrylatecopolymers or may be a water dispersible polyurethane.

Various additives for controlling or regulating the pH of the inkjet inkcomposition of the present invention may also be used. Examples ofsuitable pH regulators include various amines such as diethanolamine andtriethanolamine as well as various hydroxide reagents. An hydroxidereagent is any, reagent that comprises an OH⁻ ion, such as a salt havingan hydroxide counterion. Examples include sodium hydroxide, potassiumhydroxide, lithium hydroxide, ammonium hydroxide, and tetramethylammonium hydroxide. Other hydroxide salts, as well as mixtures ofhydroxide reagents, can also be used. Furthermore, other alkalinereagents may also be used which generate OH⁻ ions in an aqueous medium.Examples include carbonates such as sodium carbonate, bicarbonates suchas sodium bicarbonate, and alkoxides such as sodium methoxide and sodiumethoxide. Buffers may also be added.

Additionally, the inkjet ink composition of the present invention mayfurther incorporate dyes to modify color balance and adjust opticaldensity. Such dyes include food dyes, FD&C dyes, acid dyes, direct dyes,reactive dyes, derivatives of phthalocyanine sulfonic acids, includingcopper phthalocyanine derivatives, sodium salts, ammonium salts,potassium salts, lithium salts, and the like. It is also within thebounds of the present invention to use a mixture of the pigmentsdescribed herein and modified pigments, such as modified pigmentscomprising pigments having attached at least one organic group. Themodified pigments can be prepared using the methods described in U.S.Pat. Nos. 5,554,739, 5,707,432, 5,837,045, 5,851,280, 5,885,335,5,895,522, 5,900,029, 5,922,118, and 6,042,643, and PCT Publication WO99/23174, the descriptions of which are fully incorporated herein byreference.

The inkjet ink compositions can be purified and/or classified using anymethod known in the art, including for example,ultrafiltration/diafiltration using a membrane, reverse osmosis, and ionexchange as well as filtration, centrifugation, or a combination of thetwo methods. In this way, unwanted impurities or undesirable largeparticles can be removed to produce an inkjet ink composition with goodoverall properties.

The present invention further relates to an inkjet, ink set whichcomprises various inkjet ink compositions and includes at least oneinkjet ink composition of the present invention. The inkjet inkcompositions of this set may differ in any way known in the art. Forexample, the inkjet ink set may comprise inkjet ink compositionscomprising different types and/or colors of pigments, including, forexample, an inkjet ink composition comprising a cyan pigment, an inkjetink composition comprising a magenta pigment, and/or an inkjet inkcomposition comprising a black pigment. Other types of inkjet inkcompositions may also be used, including, for example, compositionscomprising agents designed to fix the inkjet ink compositions onto thesubstrate. Other combinations will be known in the art.

The present invention will be further clarified by the followingexamples which are intended to be only exemplary in nature.

EXAMPLES Examples 1-9

The following examples describe the preparation of organic chromophoregroups having a reactive group that can be used to prepare the polymericdispersants used in the inkjet ink compositions of the presentinvention.

Example 1

A mixture of 28.4 g of 2-(4-aminophenylsulphonyl)ethane sulfuric acid(APSES), 150 mL of ice water, and 12 mL of 37% HCl was combined with 6.9g of sodium nitrite in 50 mL water. After 40 min of stirring at 5° C.,the diazotization reaction was stopped by destroying any excess nitrousacid by the addition of sulfamic acid, and this diazo-APSES solution waskept on ice until used for the coupling reaction.

A mixture of 20.7 g of acetoacet-o-anisidide (AAOA), 30 mL isopropylalcohol, and 50 mL of a 2 M NaOH solution, was heated to 70° C. todissolve the AAOA. After adding 500 mL ice water, AAOA was precipitatedas a fine dispersion by the addition of 7 mL of 100% acetic acid. Tothis was added 90 g of sodium acetate, followed by dropwise addition ofthe diazo-APSES solution at a temperature below 5° C., which resulted inthe formation of a bright yellow precipitate (AAOA-APSES). This wasallowed to stir overnight. The product was separated by centrifugation,washed with ice water, and kept as a wet paste.

To a mixture of 30.2 g of diethylenetriamine in 1 L of water was added a4N solution of sodium hydroxide to raise pH to 12.5. To this was slowlyadded a solution of 30.6 g of AAOA-APSES in 3 L of water. A yellowprecipitate formed, and the mixture was stirred overnight after theaddition was completed, centrifuged to remove excess diethylenetriamine, and washed 2 times with water. The resulting precipitate(AAOA-APSES-DETA) was filtered off and dried in high vacuum at theambient temperature for 8 hours.

Example 2

A mixture of 12.2 g of 4-aminobenzylamine (ABA, n=1) or 20.9 g of2-(4-aminophenyl)ethylamine bis-hydrochloric acid (APEA, n=2), 30 mL of37% HCl, and 150 mL of water was cooled to 5° C. and diazotized by slowaddition of a solution of 6.9 g of sodium nitrite in water. Thetemperature during the diazotization (<5° C.) was maintained by addingof 100 g of crushed ice during the reaction. After 20 min of stirring,the diazotization reaction was stopped by destroying any excess ofnitrous acid by the addition of sulfamic acid, and this diazo-ABA ordiazo-APEA solution was kept on ice until used for the couplingreaction.

A mixture of 20.7 g of acetoacet-o-anisidide (AAOA), 300 mL of water,and 4 g of sodium hydroxide was homogenized in a sonic bath until aclear solution formed. Then AAOA was reprecipitated by addition of 6 mLof concentrated acetic acid, followed by 60 mL of saturated solution ofsodium acetate. The mixture was diluted with 1 L of ice water and cooledto 5° C. To this mixture was added the diazo-ABA or diazo-APEA solution,which was added dropwise over 1 hour while maintaining the pH at 4.9-5.1by adding small amounts of sodium acetate. The viscous coupling mass wasdiluted with 1 L of ice water and stirred for an additional hour. Afterthis, the pH was raised to 12 by addition of a 2M sodium hydroxidesolution. The resulting precipitate (AAOA-ABA or AAOA-APEA) was filteredoff, washed with 2 L of ice water having a pH of 10, and finally washedwith an additional 2 L of DI water. The material was dried in a vacuumoven at 60° C. for 48 hours. HPLC analysis of the crude material showedno impurities, and ¹H-NMR analysis was consistent with the desiredproduct.

Example 3

Seventeen grams of dry quinolonoquinone were stirred with 170 g ofconcentrated sulfuric acid at room temperature until completedissolution of the solid material was achieved. After this, 12.5 g ofN-hydroxymethylphthalimide was added. The resulting mixture was stirredat 60° C. for 3 hours, allowed to cool to room temperature, and pouredinto 2.5 L of ice water. The resulting precipitate(phthalimidomethylquinolonoquinolone) was filtered off and washed withwater to a pH of approximately 6. The solidphthalimidomethylquinolonoquinolone was dried in the vacuum oven toconstant weight.

A mixture of 10 g of phthalimidomethylquinolonoquinolone and 50 mL of a20% NaOH solution was stirred at 85° C. for 3 hours. Then, 75 mL of a20% HCl solution was added, and the mixture was stirred at 85° C. for anadditional 3 hours. The mixture was cooled to room temperature andneutralized with a 20% NaOH solution. The resulting precipitate wasfiltered off, washed with water, and dried to obtain 5.9 g of a yellowpowder. ¹H-NMR and mass-spectral data showed that the product wasprimarily the desired mono-(aminomethyl)-quinolonoquinolone (AMQQ)

Example 4

Polyphosphoric acid (500 g, 84% min P₂O₅) was heated to 110° C., and 21g of 2-ethoxycarbonyl-3-anilinoquinoline-4(1H)-one was added over a 10minute period. The temperature was raised to 150° C., and the mixturewas stirred for three hours to complete the cyclization. Then themixture was cooled to 50° C., and 10.5 g of paraformaldehyde and 33.4 gof 2,2,2-trichloroacetamide were added. The temperature was then raisedto 85° C., and the reaction mixture was stirred for 3 hours at thistemperature. The hot melt was poured into 2000 mL of warm DI water. Theresulting yellow precipitate of2,8-bis-(trichloroacetylamidomethyl)quinolonoquinolone was filtered offand washed with hot water to a pH >4.0. The yield was close to 97%, andthe product was used in the next step (hydrolysis) without furtherpurification.

The crude 2,8-bis-(trichloroacetylamidomethyl)quinolonoquinolone (24 g)was hydrolyzed by mixing with 400 mL of water and 100 mL of a 6M NaOHsolution. The mixture was refluxed for 6 hours, cooled to roomtemperature, and neutralized with a 4M HCl solution to a pH of 6. Theresulting precipitate was filtered off to give 80.5% of2,8-bis-(aminomethyl)quinolonoquinolone (2AMQQ)

Example 5

A mixture of 150 g of 100% sulfuric acid, 10 g of copper phthalocyanine,15.25 g of phthalimide, 5.5 g of paraformaldehyde, and 5.0 g ofphosphorus pentoxide was heated at 75° C. for 4 hours. The mixture waspoured into 1000 g of ice water. The resulting precipitate was filteredoff and washed to a pH of approximately 6. The solid(phthalimidomethyl-CuPc) was slurried with acetone and filtered to give15 g (97%) of a dark blue powder.

A mixture of 140 g of 100% sulfuric acid and 10 g ofphthalimidomethyl-CuPc was heated at 100° C. for 4 hours. The mixturewas poured into 1000 g of ice water. The resulting precipitate wasfiltered off, washed to a pH of 3, and dried to give 11.2 g (91.8%) ofpartially hydrolized product.

A mixture of 10 g of the partially hydrolyzed product and 300 mL of a0.2M sodium hydroxide solution was refluxed for 1.5 hours. Then a 6M HClsolution was added slowly at 90-95° C. until the pH was 1. The initiallyformed precipitate gradually redissolved. The mixture was then refluxedfor another 6 hours. Concentrated HCl (40 mL) was then added, and themixture was cooled to form a precipitate, which was filtered off,yielding 31 g (93.5%) of the hydrochloride salt of aminomethyl copperphthalocyanine (AMPc).

Example 6

Twenty eight grams of quinacridone were dissolved in 320 g of 98%sulfuric acid. Then. 16.5 g of hydroxymethylphthalimide was added. Themixture was heated at 56° C. for 3 hours and then poured into 2.5 kg ofice-water. The resulting precipitate (phthalimidomethylquinacridone) wasfiltered off, washed with water to a pH of approximately 6, and dried,yielding 46 g of crude 2-phthalimidomethylquinacridone (the expectedisomer based on the directing effects of both the amino and carbonylgroups).

A mixture of 30 g of crude phthalimidomethylquinacridone and 85 mL of a20% NaOH solution was heated at 85° C. for 3. hours. Then 120 mL of a20% HCl solution was introduced, and the same temperature was maintainedfor 3 more hours. The cooled solution was neutralized with a dilutesodium hydroxide solution to a pH of approximately 6. The resultingprecipitate was filtered off, washed with water, and dried under vacuum,yielding 10 g of 2-aminomethylquinacridone (AMQA).

Example 7

Dimethyl succinoylsuccinate, (70.37 g, 0.308 mol), 4-toluidine (74.1 g,0.692 mol), absolute ethanol (700 mL), and concentrated hydrochloricacid (1.7 mL) were placed into a flask equipped with an overheadmechanic stirrer and reflux condenser. The mixture was heated at refluxwith stirring for 8 hour under nitrogen atmosphere. The reaction mixturewas then cooled to room temperature, and to this was added sodium3-nitrobenzenesulfonate (76 g, 0.31 mol) and 43 g of sodium hydroxide in70 mL of water. This was then heated at reflux for 4 hours. Water (250mL) was added, and the mixture turned into clear solution which wasfiltered to remove any insoluble material. The filtrate was diluted to2500 mL with DI water and neutralized with concentrated sulfuric acid topH 2 to obtain 2,5-bis-p-tolylaminoterephthalic acid as a purpleprecipitate, which was filtered off, washed with DI water to pH >5, anddried in a vacuum oven (55° C.) for 2 days. Yield was 114.0 g (97.7%) ofpurple solid. ¹HNMR (DMSO-d6) spectrum was consistent with the desiredproduct.

Polyphosphoric acid (369 g, 84% min. P₂O₅) was warmed to 110° C. undermechanical stirring, and 2,5-bis-p-tolylaminoterephthalic acid (15.7 g,0.042 mol) was added. The resulting mixture was stirred and heated at160° C. for 3 hours. Then, the mixture was cooled to 50° C., andparaformaldehyde (1.9 g, 0.063 mol) and trichloroacetamide (7.5 g, 0.046mol) were added. Heating was continued at 75° C. for 3 hours. Themixture was poured into 1000 mL of DI water, and the magenta precipitatewas filtered off and washed with water to pH >4. The precipitate is thenwashed with ethanol until the filtrate ran clear. The resultingprecipitate, (trichloroacetamidomethyl)dimethylquinacridone, was driedin the vacuum oven (60° C.) overnight. Yield was 20.5 g of magentapowder (95%). Elemental analysis: Cl: 19.80, N: 7.70; Calculated: Cl:20.66, N: 8.16.

(Trichloroacetamidomethyl)dimethylquinacridone (10 g, 0.0194 mol) and100 mL of N-methylpyrrolidinone (NMP) were heated at 120° C. for 15minutes, after which time the solution was filtered to remove insolublematerial. Then an aqueous solution of sodium hydroxide (6N, 13.0 mL) wasadded, and the resulting mixture was heated at 120° C. under a nitrogenatmosphere overnight. The mixture was poured into 600 mL of water andcooled to room temperature. The resulting precipitate was filtered offand washed with water, and the product was dried in a vacuum oven (60°C.) overnight. The resulting product, aminomethyldimethylquinacridone(AmDMQA) contained less than 0.5% Cl, which indicated the completenessof the hydrolysis.

Example 8

To 100 g of 2-(4-methoxyphenyl)ethylamine in 500 mL of chloroform wasslowly added 100 mL of triethylamine acetic anhydride (72 g), and thiswas stirred at 20° C. for 40 minutes. The mixture was then extractedtwice with a dilute aqueous solution of HCl (0.4 N, 400 mL) followed bya saturated aqueous solution of NaHCO₃ (2×400 mL). The solvent wasremoved by rotary evaporation, and the residue was dried in a vacuumoven (45° C.), resulting in an off-white powder,N-[2-(4-methoxyphenyl)ethyl]acetamide (120 g, 93.9% yield). ¹HNMR(DMSO-d6) spectrum was consistent with the desired product.

A solution of 70 g of N-[2-(4-methoxyphenyl)ethyl]acetamide in 330 mL ofacetic acid was introduced slowly into 350 mL of 70% nitric acid so thatthe temperature was between 30-35° C. The addition process took 1 hour.The mixture was stirred at 30-35° C. for additional 40 minutes and wasthen poured into 1500 mL of ice water. The resulting slurry wasextracted with chloroform (2×400 mL). The organic phase was extractedwith a saturated aqueous solution of NaHCO₃ (2×400 mL) and then withwater (2×400 mL). The solvent was then removed by rotary evaporation toproduce 65 g of N-[2-(4-methoxy-3-nitrophenyl)ethyl]acetamide, which wasfurther purified by recrystallization from ethyl acetate to yield 48 g(55.6% yield) of yellow crystals. ¹HNMR (DMSO-d6) spectrum wasconsistent with the desired product.

N-[2-(4-methoxy-3-nitrophenyl)ethyl]acetamide (7.4 g) in 150 mL ofethanol was hydrogenated in the presence of 3.5 mL of concentrated HCland 0.4 g of 10% Pd/C at 30-40 psi for 3 hours in a Parr shaker. Afterthis time, the catalyst was filtered off and the solvent was removed byrotary evaporation to yield 7.1 g ofN-[-2-(3-amino-4-methoxyphenyl)ethyl]acetamide hydrochloride as anoff-white solid (94.0% yield). ¹HNMR (DMSO-d6) spectrum was consistentwith the desired product.

N-[-2-(3-amino-4-methoxyphenyl)ethyl]acetamide hydrochloride (19 g) wasmixed with 40 mL N,N-dimethylformamide and 18 g of diketene followed byslow addition of 3 mL of triethylamine. The mixture was stirred at80-85° C. for 30 minutes and then poured into 300 mL of water. Theaqueous solution was extracted with chloroform (2×200 mL) and thesolvent was removed by rotary evaporation to yield 21.9 g (96.5%) ofN-[5-(2-acetylaminoethyl)-2-methoxyphenyl]-3-oxo-butyramide as a lightyellow oil. ¹HNMR (DMSO-d6) spectrum was consistent with the desiredproduct.

N-[5-(2-acetylaminoethyl)-2-methoxyphenyl]-3-oxo-butyramide (6.93 g),dissolved in 150 mL of water by addition of 2 mL of a 2N NaOH solution,was cooled in an ice bath (<5° C.), and acetic acid was added slowly topH 5, so the coupler reprecipitated in a fine crystalline form. Thensodium acetate was added to bring the coupler dispersion to a pH of 5.5.

4-Nitro-2-anisidine (4 g) was mixed with 75 g of ice-water and 7.1 mL ofconcentrated HCl. The mixture was diazotized at below 5° C. with asolution of 1.64 g of NaNO₂ in 30 mL of ice water. Excess nitrous acidwas destroyed by addition of sulfamic acid. The diazotized4-nitro-2-anisidine solution was added to the coupler dispersion over 20minutes with vigorous stirring. The mixture was kept at pH >5 byaddition of solid sodium acetate as needed. The temperature wasmaintained below 5° C. by outside cooling with ice.

After the diazonium solution addition was complete, the reaction mixturewas allowed to warm to room temperature and was stirred overnight at 20°C. and for 20 minutes at 60° C. The resulting precipitate was filter offand washed with D.I. water, yieldingN-[5-(2-acetamidoethyl)-2-methoxyphenyl]-2-[(2-methoxy-4-nitrophenyl)-hydrazono]-3-oxobutyramideas a brown presscake (9.77 g, 87.4% yield). ¹HNMR (DMSO-d6) spectrum wasconsistent with the desired product.

The product described in the previous step,N-[5-(2-acetamidoethyl)-2-methoxyphenyl]-2-[(2-methoxy-4-nitronitrophenyl)-hydrazono]-3-oxobutyramide(4.6 g) was mixed with 150 mL of NMP and 20 mL of concentrated HCl andheated at 112° C. for 6 hours. The reaction mixture was poured into 1000mL of water and left overnight. The resulting precipitate was filteredoff, washed with water and then with a dilute aqueous NaHCO₃ solution toa neutral pH, and finally dried in a vacuum to give 4.0 g (95.2%) ofN-[5-(2-aminoethyl)-2-methoxyphenyl]-2-[(2-methoxy-4-nitro-phenyl)-hydrazono]-3-oxo-butyramide(AePY74) as a yellow powder. ¹NMR (DMSO-d6) spectrum was consistent withthe desired product.

Example 9

N-[-2-(3-amino-4-methoxyphenyl)ethyl]acetamide hydrochloride, preparedas described in Example 8 (15 g) and 175 mL of 2N HCl were heated atreflux for 6 hours. The solvent was removed by rotary evaporation, andthe residue was washed with ethanol. The resulting white precipitate wasfiltered off and dried in vacuum, yielding 13.7 g (94%) of5-(2-aminoethyl)-2-methoxyphenylamine (AMMPA) dihydrochloride as whitecrystals. ¹HNMR (DMSO-d6) spectrum was consistent with the desiredproduct.

5-(2-Aminoethyl)-2-methoxyphenylamine (AMMPA) dihydrochloride (4.02 g)was dissolved in 55 mL of ice water with 5 mL of conc. HCl, and thesolution was cooled in an ice bath to below 5° C. The amine wasdiazotized with 1.17 g of NaNO₂ dissolved in 15 mL of water. The mixturewas stirred at below 5° C. for 20 minutes, and any excess nitrous acidwas destroyed by addition of sulfamic acid.

Acetoacet-o-anisidide (AAOA, 3.48 g) was dissolved in a mixture of 50 mLof water and 0.84 g of NaOH. The solution was cooled to 5° C., and thecoupler was reprecipitated by addition of acetic acid to pH 5. Then, asaturated aqueous solution of sodium acetate was added to adjust the pHto 5.6. To this mixture was added the diazonium salt solution of AMMPAdropwise. A yellow precipitate forms instantly. The mixture was stirredat room temperature for 3 hours, and the precipitate was filtered offand washed with water, yielding 6.45 g (98%) of2-{[5-(2-aminoethyl)-2-methoxyphenyl]-hydrazono}-N-(2-methoxyphenyl)-3-oxo-butyramide(AAOA-AMMPA) as a yellow solid. ¹HNMR (DMSO-d6) spectrum was consistentwith the desired product.

Examples 10-15

The following examples describe the preparation of polymeric dispersantsuseful in the inkjet ink compositions of the present inventioncomprising a polymeric group and at least one group comprising a linkinggroup and an organic chromophore group.

Example 10

Fifty grams of Joncryl 683 (a styrene-acrylic acid polymer availablefrom Johnson Polymers having an acid number of 165 and a M_(w) of7000-9000) and 1.925 g of N-hydroxysuccinimide (HOSI) were dissolved in200 mL of dry THF. To this, a solution of 3.45 g ofN,N′-dicyclohexylcarbodiimide in 50 mL of THF was added dropwise over aperiod of 5-10 min. Stirring at room temperature was continued for 5hours. The resulting precipitate of N,N′-dicyclohexylurea was filteredoff. To the filtrate, containing HOSI-activated polymer, was added 6.76g of AAOA-APSES-DETA (Example 1), and the mixture was refluxed for 5hours. The resulting polymeric dispersant solution was evaporated on arotary evaporator to remove the bulk of THF. The residue was treatedwith a solution of 5 g NaOH in 125 mL water, and the mixture wascentrifuged to remove insoluble material. The transparent supernatant,which was a solution a polymeric dispersant comprising a polymeric groupand an organic chromophore group (AAOA-APSES-DETA-J683) sodium salt, wasused without further purification.

Example 11

One hundred grams of Joncryl® 683 (a styrene-acrylic acid polymeravailable from Johnson Polymers having an acid number of 165 and a M_(w)of 7000-9000), 8.8 g AAOA-ABA (Example 3), and 5.36 g ofN,N′-dicyclohexylcarbodiimide were dissolved in 500 mL of dryN-methylpyrrolidinone. The mixture was stirred for 48 hours at roomtemperature with protection against atmospheric moisture. The resultingN,N′-dicyclohexylurea precipitate was filtered off, and the filtrate wasadded dropwise to 4 L of water while stirring. A flaky yellowprecipitate formed. Then the pH was lowered to 2, and the resultingpolymeric dispersant comprising a polymeric group and an organicchromophore group (AAOA-ABA-J683) was filtered off. This was washed with4 L of water and allowed to dry on the filter funnel overnight. Theyield was nearly quantitative. Analysis by GPC indicated thatapproximately 96% of AAOA-ABA was covalently attached to the polymer.

Example 12

The procedure described in Example 11 was followed, with the exceptionthat AMQQ (Example 4) was used instead of AAOA-ABA (Example 3). Theresulting polymeric dispersant comprising a polymeric group and anorganic chromophore group. (AMQQ-J683) was obtained in similar yieldsand with similar levels of attached chromophore groups.

Example 13

The procedure described in Example 11 was followed, with the exceptionthat AMQA (Example 6) was used instead of AAOA-ABA (Example 3). Theresulting polymeric dispersant comprising a polymeric group and anorganic chromophore group (AMQA-J683) was obtained in similar yields andwith similar levels of attached chromophore groups..

Example 14

A mixture of 9.6 g of AMPc hydrochloride (Example 5), 84 g of Joncryl®683 (a styrene-acrylic acid polymer available from Johnson Polymershaving an acid number of 165 and a M_(w) of 7000-9000), 2 g oftriethylamine, and 250 mL of xylene was heated at reflux for 8 hours.The resulting water formed during the reaction was removed using aDean-Stark apparatus. The resulting gummy product solidified as it wascooled to room temperature. The solvent was decanted from the solid, andthe solid was dried in a vacuum oven, yielding 114 g of dark blue crudepolymer.

Ten grams of this crude product was purified by dissolving in 120 mL ofa 0.2M NaOH solution at 70° C., filtering the solution, and finallyneutralization with a 2 N HCl solution. The resulting dark bluepolymeric precipitate was filtered off, washed with water and dried invacuum oven to obtain 6.8 g of dark blue solid, a polymeric dispersantcomprising a polymeric group and an organic chromophore group(AMPc-J683).

Example 15

The procedure described in Example 14 was followed, with the exceptionthat 2AMQQ (Example 4) was used instead of AMPc hydrochloride (Example5) and Joncryl® 690 acrylic polymer (a styrene-acrylic acid polymeravailable from Johnson Polymers having an acid number of 240 and a M_(w)of approximately 16000) was used instead of Joncryl® 683 acrylicpolymer, resulting in the formation of a polymeric dispersant comprisinga polymeric group and an organic chromophore group (2AMQQ-J690).

Example 16

This example describes the preparation of a polymeric dispersantcomprising a polymer and an attached group that is not an organicchromophore group.

The procedure described in Example 11 was followed, with the exceptionthat 5-aminobenzimidazolone (ABI) was used instead of AAOA-ABA (Example3). The resulting polymeric dispersant comprising a polymeric group andan organic group, capable of hydrogen bond forming, but not specificallyrelated to any chromophore group (ABI-J683) was obtained in similaryields and with similar levels of attached ABI group.

Example 17 and Comparative Examples 1-2

The following examples demonstrate improved properties of an inkjet inkcomposition of the present invention, comprising a pigment and apolymeric dispersant that comprises a polymeric group and an organicchromophore group.

A mixture of 29 g of Pigment Yellow 74, 500 mL of water, and adispersant was mixed using a Silverson® rotor-stator high shear mixer at6,500 rpm for 2 hours. For Example 17, 10 g of the polymeric dispersantof Example 10 (AAOA-APSES-DETA-J683) was used. For Comparative Example1, a combination of 1.35 g of AAOA-APSES-DETA (Example 1) and 10 g ofJoncryl® 683 acrylic polymer Na⁺ salt was used. For Comparative Example2, 10 g of Joncryl® 683 acrylic polymer Na⁺ salt was used. For each, theresulting mixture was sonicated using a Misonix immersing sonicator for30 min. Excess dispersant was removed by diafiltration using 10 volumesof a 0.1 M NaOH solution followed by 10 volumes of DI water using amembrane filter. The resulting yellow dispersion was concentrated to10-12% solids, and the average particle size was measured using a UPAMicrotrac laser scattering equipment. Results are shown below in theTable 1.

TABLE 1 Example # Dispersant Mean Particle Size Ex 17AAOA-APSES-DETA-J683  88 nm Comp Ex 1 Joncryl ® 683 Na⁺ salt + 138 nmAAOA-APSES-DETA 1.35 g Comp Ex 2 Joncryl ® 683 Na⁺ salt; No dispersionformed

As the data shows, a yellow pigment dispersion prepared using apolymeric dispersant comprising a polymeric group and an organicchromophore group (Example 17) has a lower particle size compared to adispersion prepared using the same polymer and organic chromophoreseparately (Comparative Example 1). The particle size of the dispersionof Example 17 was less than 100 nm while that of Comparative Example 1was greater than 100 nm. In addition, the dispersion of Example 17 wasalso found to be more thermally stable than that of ComparativeExample 1. No stable dispersion resulted using a polymeric dispersantwithout an attached organic chromophore group (Comparative Example 2).Thus, it has surprisingly been found that improved properties resultusing a polymeric dispersant comprising an attached organic chromophoregroup. Based on this data, it would be expected that the dispersion ofExample 17 could be used as an inkjet ink composition of the presentinvention.

Examples 18-23 and Comparative Examples 3-4

The following examples describe the preparation of inkjet inkcompositions of the present invention (Examples 18-23) as well ascomparative inkjet ink compositions (Comparative Examples 3 and 4).

An attritor (type 01STD from Union Process, Akron, Ohio) was chargedwith 10 g pigment (either dry or as a presscake, the amount of which wasdetermined by its solids content), 100 mL water, and 500 g of zirconiumsilicate beads (0.07-0.125 mm). Five grams of a polymeric dispersantcomprising a polymeric group and an organic chromophore group was thenadded. For each example, the specific type of pigment and the specificpolymeric dispersant are shown in Table 2 below. PY 74 is Pigment Yellow74, which is an azo pigment. PR 122 is Pigment Red 122, which is aquinoacridone pigment PB 15:4 is Pigment Blue 15:4, which is aphthalocyanine pigment (cyan). Finally, PY 218 and PY 220 are PigmentYellow 218 and 220, which are quinolonoquinolone pigments. PY 218 is3-fluoroquinolonoquinolone and PY 220 is 2-fluoroquinolonoquinolone.

As shown for Example 18, the dispersant was added as a solution in 25 mLof methyl ethyl ketone (MEK), followed by an appropriate amount of a 1 MNaOH solution to neutralize all of the acid groups in the polymer. ForExamples 19-23 and Comparative Examples 3-4, the polymeric dispersantwas solubilized with the appropriate amount of a 1 M NaOH solution priorto adding to the attritor, without the use of methyl ethyl ketone.

Once these components were combined, mixing at 600 rpm began, and anadditional 500 g of beads were also added. After mixing for 2 hours, themedia was filtered off using a coarse fitted filter, and the media waswashed with 200 mL of water.

For Example 18, the MEK was removed by evaporation under vacuum. Forsome of the examples, the resulting dispersion was sonicated for 1-3hours until 50% of the particle size fell below 100 nm, as measured by aUPA Microtrac laser scattering equipment. These examples are identifiedin Table 2 below.

Each dispersion was centrifuged at 4,500 rpm for 40 min to remove tracesof media and coarse particles and then concentrated using membranediafiltration to a final concentration of approximately 10% solids. Theaverage particle size of these dispersions was measured using a UPAMicrotrac laser scattering equipment, and the results are shown below inthe Table 2 below.

TABLE 2 Polymeric Soni- Dispersion Particle Ex # Pigment Dispersant MEKcation yield % size 18 PY 74 AAOA-ABA- Yes 0 hrs 95 106 nm J683 (Example8) 19 PR 122 AMQA-J683 No 0 hrs 95 100 nm (Example 10) 20 PB 15:4AMPc-J683 No 0.5 hrs 93 107 nm (Example 11) 21 PY 220 AMQQ-J683 No 1 hrs95  91 nm (Example 9) 22 PY 218 AMQQ-J683 no 0.5 hrs 95  92 nm (Example9) 23 PY 218 2AMQQ-J690 no 2 hrs 95 100 nm (Example 12) Comp PY 218ABI-J683 no 2 hrs 90 140 nm Ex 3 (Example 14) Comp PY 74 J683 no 1 hr 90140 nm Ex 4

As the data shows, the particle size of the dispersions of Examples18-23 are very small, indicating that each of these dispersions could beused as an inkjet ink composition. Thus, the data also shows that, if apigment comprising a colorant having an organic chromophore group iscombined with a polymeric dispersant comprising a polymeric group and,an organic chormophore group that is similar to that of the colorant, astable inkjet ink composition results. In particular, for Examples 21and 22, both types of quinolonquinolone pigments were well dispersedusing the same polymer dispersant, comprising a quinolonoquinolonylgroup. Without wishing to be bound by theory, it is believed that thesepolymeric dispersants may provide stable dispersions by interaction withthe pigment, such as through hydrogen bonding. When no specificinteraction is present, larger particle sizes result. This is shown byComparative Example 3 and 4, in which polymeric dispersants are usedthat do not comprise an organic chromophore group. The resultingparticle sizes are considerably higher. Also, in Comparative Example 3,since the ABI group is expected to hydrogen bond with PY 218, theresults suggest that the interaction between the organic chromophoregroup of the polymeric dispersant used in Examples 22 and 23 may bethrough co-crystallization, either alone or in combination with hydrogenbonding.

Example 24-29 and Comparative Example 5-6

The following examples demonstrate the print performance of inkjet inkcompositions of the present invention (Examples 24-29) as well ascomparative inkjet ink compositions (Comparative Examples 5 and 6).

Inkjet ink compositions were formulated using 10% by weight glycerol, 5%by weight triethyleneglycol, 1% by weight Surfynol® 465 surface activeagent, and 4% by weight pigment, with the balance of the composition,being water. Each of the compositions of Examples 18-23 (for Examples24-29) and Comparative Examples 3 and 4 (for Comparative Examples 5 and6) were used. The resulting inkjet ink compositions were printed usingan Epson C86 printer.

For Examples 24-29, the inks printed reliably, providing saturated colorprints. Virtually no striping and banding was observed when printed onthe following substrates: Xerox 4024, Xerox Recycled, Hammermill CopyPlus, HP Advanced, Great White, Epson InkJet Photo Quality Paper, EpsonPremium Glossy Photo Paper, and Canon PR-101 Photo Paper. Thus, the inkjet ink compositions of the present invention produce images having goodoverall properties.

The inkjet ink compositions of Examples 24-29 and Comparative Examples5-6 were evaluated for shelf life stability by subjecting thecompositions to heat aging at 70° C. during 6 weeks. Particle sizegrowth was monitored using a UPA Microtrac laser scattering equipment.For the inkjet ink compositions of the present invention (Examples24-29) in which a polymeric dispersant comprising an organic chromophoregroup was, the average particle size growth was no more than 10%,whereas for the comparative inkjet ink compositions (ComparativeExamples 5 and 6), where a different polymeric dispersant was used,particle size growth exceeded 50%. Thus, the inkjet ink compositions ofthe present invention have surprisingly been found to have improvedproperties over comparative inkjet ink compositions.

Examples 30-32

The following examples describe the preparation of polymeric dispersantsuseful in the inkjet ink compositions of the present inventioncomprising a polymeric group and at least one group comprising a linkinggroup and an organic chromophore group.

Example 30

To a 300 mL round bottom flask equipped with a Claisen adaptor, dryingtube and thermocouple was added N-methylpyrrolidinone (NMP, 100 mL,Fisher Chemical certified A.C.S. grade), SMA3000 UFP@ (a styrene-maleicanhydride polymer available from Sartomer, x:y=3:1, 10 g, 24.4 mmolmaleic anhydride), AAOA-APEA from Example 2 (A′CH₂NH₂, 1 g, 2.8 mmol),and triethylamine (0.39 mL, 2.8 mmol, Aldrich supplier 99.5% product ofAtofina Chemical Company). The solution was then heated to 70-90° C. andallowed to stir over two days. After this time, the reaction mixture wasallowed to cool to room temperature, and the product was precipitated byadding the mixture to a solution of HCl (15 mL) and DI water (750 mL).The crude polymeric dispersant was then filtered and washed with DIwater (2×300 mL), yielding of a polymeric dispersant comprising apolymeric group and an organic chromophore group (AAOA-APEA-SMA), as awet cake (29.4% wt. percent solids). Analysis by gel permeationchromatography (GPC) indicated that approximately 72% of the AAOA-APEAwas attached to the polymer.

Example 31

A polymeric dispersant was prepared using the procedure described inExample 30, with the exception that A′CH₂NH₂ is AmDMQA from Example 7 (1g, 2.9 mmol) instead of AAOA-APEA, resulting in the formation ofpolymeric dispersant comprising a polymeric group and an organicchromophore group (AmDMQA-SMA).

Example 32

A polymeric dispersant was prepared using the procedure described inExample 30, with the exception that A′CH2NH₂ is AmDMQA from Example 7 (1g, 29 mmol) instead of AAOA-APEA, and SMA EF40 (a styrene-maleicanhydride polymer available from Sartomer, x:y=4:1, 10 g, 19.5 mmolmaleic anhydride) was used instead of SMA3000, resulting in theformation of polymeric dispersant comprising a polymeric group and anorganic chromophore group (AmDMQA-EF).

Examples 33-34

The following examples describe the preparation of polymeric dispersantsuseful in the inkjet ink compositions of the present inventioncomprising a polymeric group and at least one group comprising a linkinggroup and an organic chromophore group and further comprising at leastone pendant group attached to the polymeric group.

Example 33

To a 300 mL round bottom flask equipped with a Claisen adaptor, dryingtube and thermocouple was added N-methylpyrrolidinone (NMP, 100 mL,Fisher Chemical certified A.C.S. grade), SMA EF40 (a styrene-maleicanhydride polymer available from Sartomer, x:y=4:1, 25 g, 48.75 mmolmaleic anhydride), AAOA-APEA from Example 2 (A′CH₂NH₂, 2.5 g, 6.7 mmol),and triethylamine (0.90 ml, 6.7 mmol, Aldrich supplier 99.5% product ofAtofina Chemical Company). The solution was then heated to 70-90° C. andallowed to stir overnight. The next day, heptylamine (NH₂—R, 5.18 g, 45mmol) was added along with an additional portion of triethylamine (6.3mL, 45 mmol), and this was allowed to stir overnight. The next day, thereaction mixture was allowed to cool to room temperature, and theproduct was precipitated by adding the mixture to a solution of HCl (15mL) and DI water (750 mL). The crude polymeric dispersant was thenfiltered, washed with DI water (2×300 mL), and dried under vacuum,yielding of a polymeric dispersant comprising a polymeric group, anorganic chromophore group, and a pendant amine group (AAOA-APEA-C7N-EF).

In addition, a variety of polymeric dispersants, having differentpendant groups, could be prepared, by this procedure using amines havingfrom 1 to 18 carbon atoms.

Example 34

A polymeric dispersant was prepared using the procedure described inExample 32, with the exception that A′CH₂NH₂ is AmDMQA (from Example 7,2.5 g, 6.7 mmol) instead of AAOA-APEA and nonylamine (NH₂—R, 6.45 g, 45mmol) was used instead of heptylamine, resulting in the formation ofpolymeric dispersant comprising a polymeric group, an organicchromophore group, and a pendant amine group (AmDMQA-C9N-EF).

Examples 35-42 and Comparative Examples 7-11

The following examples demonstrate improved properties of an inkjet inkcomposition of the present invention, comprising a pigment and apolymeric dispersant that comprises a polymeric group and an organicchromophore group.

Pigment dispersions were prepared using one of the following methods.

Method 1

In an attritor bowl (Szegvari Attritor System) filled to half volumewith zirconium silicate bead milling media (0.07 mm-0.125 mm) was added10 g of pigment with stirring (600 rpm). In a separate beaker, 5 g ofdispersant was dissolved in aqueous base (1 M sodium hydroxide, base,equivalency 2.5 times the molar maleic anhydride content) with heat(approximately 60° C.). The aqueous dispersant solution was then addedto the attritor bowl, and the milling mixture was diluted withapproximately 200 mL of DI water to promote efficient and fluid milling.The attritor was allowed to operate for approximately one hour. Afterthis time the zirconium silicate media was filtered off and rinsedseveral times with additional DI water (3×100 mL). The rinses werecombined with, the dispersion, and the total volume of pigmentdispersion was then sonicated at a maximum power of 60 W (MisonixSonicator 3000, Model S-3000, Mixonix Inc.) to reduce particle size to<150 nm. The pigment dispersion was then diafiltered to increase theconcentration to approximately 10-15% and then further diafiltered withDI water (5 volumes). The dispersion was then centrifuged at 4500 RPMfor 45 min at 5° C. using a temperature controlled Sorval StratosCentrifuge to reduce the amount of large particles, yielding the finalpigment dispersion (10-15% solids).

Method 2

In an attritor bowl (Szegvari Attritor System) filled to half volumewith zirconium silicate bead milling media (0.07 mm-0.125 mm) was added10 g of pigment with stirring (600 rpm). In a separate beaker, 5 g ofdispersant was dissolved in an organic co-solvent (approximately 20-50mL of methyl ethyl ketone (MEK), although other co-solvents such asN-methylpyrrolidinone (NMP) and 2-pyrrolidone (2P) could also be used)with heat (approximately 60° C.). Aqueous base was added to the attritorbowl (1 M sodium hydroxide, base equivalency 2.5 times the molar maleicanhydride content) followed by the dispersant solution, and the millingmixture was then diluted with approximately 150-200 mL of DI water topromote efficient and fluid milling. The attritor was allowed to operatefor approximately one hour. After this time, the zirconium silicatemedia was filtered off and rinsed several times with additional DI water(3×100 mL). The rinses were combined with the dispersion, and the totalvolume of pigment dispersion was diafiltered to increase theconcentration to approximately 10-15% and then further diafiltered withDI water to remove traces of organic co-solvent (5 volumes). Thedispersion after diafilteration was concentrated down to 14-16% solidsand then sonicated at a maximum power of 60 W (Misonix Sonicator 3000,Model S-3000, Mixonix Inc.) to reduce particle size to <150 nm). Thedispersion was then centrifuged at 4500 RPM for 45 min at 5° C. using atemperature controlled Sorval Stratos Centrifuge to reduce the amount oflarge particles, yielding the final pigment dispersion (10-15% solids).

Method 3

In a beaker, 5 g of dispersant and 10 g of pigment were combined in 150g of an organic co-solvent (methyl ethyl ketone (MEK), although otherco-solvents such as N-methylpyrrolidinone (NMP) and 2-pyrrolidone (2P)could also be used) with heat (approximately 60° C.) and was added to anattritor bowl (Szegvari Attritor System) filled to half volume withzirconium silicate bead milling media (0.07 mm-0.125 mm) with stirring(600 rpm). The attritor mill was allowed to operate for 30 min at 600rpm, and then aqueous base was added (1 M sodium hydroxide, baseequivalency 2.5 times the molar maleic anhydride content). After thebase was added, the attritor bowl was deluged with 100-150 mL of DIwater, subsequently inverting phases from organic to aqueous. Theattritor was then allowed to operate for approximately one hour further.After this time, the zirconium silicate media was filtered off andrinsed several times with additional DI water (3×100 mL). The rinseswere combined with the dispersion, and the total volume of pigmentdispersion was diafiltered to increase the concentration toapproximately 10-15% and then further diafiltered with DI water toremove traces of organic co-solvent (5 volumes). The dispersion was thenconcentrated down to 14-16% solids and then sonicated at a maximum powerof 60 W (Misonix Sonicator 3000, Model S-3000, Mixonix Inc.) to reduceparticle size to <150 nm. The dispersion was then centrifuged at 4500RPM for 45 min at 5° C. using a temperature controlled Sorval StratosCentrifuge to reduce the amount of large particles, yielding the finalpigment dispersion (10-15% solids).

Method 4

In a beaker, 5 g of dispersant and 10 g of pigment were combined) in 150g of an organic co-solvent (methyl ethyl ketone (MEK), although otherco-solvents such as N-methylpyrrolidinone (NMP) and 2-pyrrolidone (2P)could also be used) with heat (approximately 60° C.). Once homogeneous,this was then added slowly to a beaker of aqueous base (450 g, baseequivalency 2.5 times the molar maleic anhydride content) equipped witha rotostator blender at maximum stirring. After complete addition, therotostator was allowed to operate for an additional 10 minutes. Then therotostator was stopped and rinsed several times with additional DI water(3×100 mL). The rinses were combined with the dispersion, and the totalvolume of pigment dispersion was diafiltered to increase theconcentration to approximately 10-15% and then further diafiltered withDI water to remove traces of organic co-solvent. (5 volumes). Thedispersion was then concentrated down to 14-16% solids and.thensonicated at a maximum power of 60 W (Misonix Sonicator 3000, ModelS-3000, Mixonix Inc.) to reduce particle size to <150 nm). Thedispersion was then centrifuged at 4500 RPM for 45 min at 5° C. using atemperature controlled Sorval Stratos Centrifuge to reduce the amount oflarge particles, yielding the final pigment dispersion (10-15% solids).

Specific pigments and dispersants used for each example, along with theresulting particle size (mv, in microns) are shown in Table 3 below.

TABLE 3 Particle Example # Pigment Dispersant Method size 35 PY 74AAOA-APEA-SMA (Ex 30) 1 0.1228 36 PY 74 AAOA-APEA-C7N-EF (Ex 33) 10.1456 Comp PY 74 SMA3000 1 0.1183 Ex 7 37 PR 122 AmDMQA-SMA (Ex 31) 10.0904 Comp PR 122 SMA3000 1 0.0747 Ex 8 38 PB 15:4 AmDMQA-SMA (Ex 31) 10.1157 Comp PB 15:4 SMA3000 1 0.0855 Ex 9 39 BP700 AmDMQA-SMA (Ex 31) 10.1199 Comp BP700 SMA3000 1 0.1206 Ex 10 40 BP700 AmDMQA-EF (Ex 32) 20.1445 Comp BP700 EF40 1 0.1111 Ex 11 41 BP700 AmDMQA-C9N-EF (Ex 34) 40.1141 42 BP700 AAOA-APEA-C7N-EF (Ex 33) 3 0.1476

Thermal stability trials were conducted at 70° C. for three separateformulations of each example: the neat dispersion at 4% pigment, thedispersion at 4% pigment with 10% 1,2-hexanediol (1,2HD), and thedispersion at 4% pigment with 10% tetraethylene glycol monobutyl ether(TEGMBE). Particle size growth was monitored using a UPA Microtrac laserscattering equipment. A dispersion was considered stable when a particlesize increase of <20% was observed compared to the initial particle sizewhile a dispersion was considered unstable when a particle sizeincrease >20% was observed. Results for each dispersion are shown inTable 4 below.

TABLE 4 Example # Neat 10% 1,2-HD 10% TEGMBE 35 stable week 6 stableweek 6 stable week 6 36 stable week 6 stable week 6 stable week 6 CompEx 7 unstable week 1 unstable week 6 unstable week 1 37 stable week 6unstable week 1 stable week 6 Comp Ex 8 unstable week 4 unstable week 0unstable week 1 38 stable week 6 stable week 6 stable week 6 Comp Ex 9stable week 6 unstable week 0 stable week 6 39 stable week 6 stable week6 stable week 6 Comp Ex 10 unstable week 6 unstable week 1 unstable week1 40 stable week 4 stable week 4 stable week 4 Comp Ex 11 stable week 6unstable week 1 unstable week 1 41 stable week 2 stable week 4 stableweek 4 42 stable week 2 stable week 2 stable week 2

As the results show, yellow pigment dispersions prepared using apolymeric dispersant comprising a polymeric group and an organicchromophore group (Example 35 as well as Example 36, which furthercomprises a pendant amine group) exhibited excellent heat-agingstabilities (70° C.) after 6 weeks alone as a neat dispersion, with 10%1,2-hexanediol (HD), and with 10% triethyleneglycol monobutylether(TEGMBE). By comparison, a dispersion prepared with the same pigment anda polymeric dispersant without an organic chromophore group (ComparativeExample 7) exhibited poor heat-aging stabilities and complete failure(70° C.) after only 1 week heat aging trials either neat, with 10%1,2-hexanediol (HD), and with 10% triethyleneglycol monobutylether(TEGMBE). Furthermore, a magenta pigment dispersion prepared using apolymeric dispersant comprising a polymeric group and an organicchromophore group (Example 37) also exhibited excellent heat-agingstabilities (70° C.) after 6 weeks alone as a neat dispersion. With 10%1,2-hexanediol (HD), this dispersion exhibited significant growth overtime but not as dramatic of a growth as observed in the absence ofpigment dispersant comprising an organic chromophore group (ComparativeExample 8). With 10% triethyleneglycol monobutylether (TEGMBE), thedispersion was much more stable with only a modest particle size growthafter 6 weeks heat aging while the comparative sample failed stabilitytrials after only one week. In addition, a cyan pigment dispersioncomprising a polymeric dispersant having an organic chromophore group(Example 38) also exhibited excellent heat-aging stabilities (70° C.)after 6 weeks alone as a neat dispersion, with 10% 1,2-hexanediol (HD),and with 10% triethyleneglycol monobutylether (TEGMBE), particularlycompared to a similar dispersion prepared using a polymeric dispersantwithout an organic chromophore group (Comparative Example 9), whichexhibited poor heat-aging stability upon initial formulation with 10%1,2-hexanediol (HD). Surprisingly, improved dispersion stability wasfound whether the organic chromophore group was the same as the organicchromophore group of the colorant of the pigment (Examples 35-37) orwhether they were different groups (Example 38).

In addition, it has also surprisingly been found that stable blackdispersions can be formed comprising carbon black and a polymericdispersant having an organic chromophore group. This is shown by Example39 and Example 40. These black dispersions, which include either amagenta or yellow organic chromophore group, exhibited excellentheat-aging stabilities (70° C.) after 6 weeks alone as a neatdispersion, with 10% 1,2-hexanediol (HD), and with 10% triethyleneglycolmonobutylether (TEGMBE). Excellent stability results were also observedwhen the polymeric dispersant further comprised a pendant amine group(Example 41 and Example 42). By comparison, dispersions of the samecarbon black with polymeric dispersants not having an organicchromophore group (Comparative Example 10 and Comparative Example 11)exhibited very poor heat-aging stabilities (70° C.) after only one weekwith 10% 1,2-hexanediol (HD) and with 10% triethyleneglycolmonobutylether (TEGMBE).

Thus, it has surprisingly been found that improved properties resultusing a polymeric dispersant comprising an attached organic chromophoregroup. Based on this data, it would be expected that the dispersions ofExamples 35-42 could be used as an inkjet ink composition of the presentinvention.

Examples 43-44

The following examples describe the preparation of polymeric dispersantsuseful in the inkjet ink compositions of the present inventioncomprising a polymeric group and at least one group comprising a linkinggroup and an organic chromophore group.

Example 43

To a 300 mL round bottom flask equipped with a condenser, nitrogen inletadaptor, and thermocouple was added N-methylpyrrolidinone (NMP, 100 mL,Fisher Chemical certified A.C.S. grade), Joncryl 683 acrylic polymer (astyrene-acrylic acid polymer available from Johnson Polymers having anacid number of 165 and a M_(w) of 7000-9000, 10 g), AAOA-APEA fromExample 2 (1 g, 2.8 mmol), and dicyclohexylcarbodiimide (DCC, 0.39 mL,2.8 mmol, available from Aldrich). The solution was then heated to85-95° C. and allowed to stir over two days. After this time, thereaction mixture was allowed to cool to room temperature and the productwas precipitated by adding the mixture to a solution of HCl (15 mL) andDI water (750 mL). The crude polymeric dispersant was then filtered andwashed with DI water (2×300 mL), yielding a polymeric dispersantcomprising a polymeric group and an organic chromophore group(AAOA-APEA-J683) as a wet cake (29.4% wt. percent solids).

Example 44

A polymeric dispersant was prepared using the procedure described inExample 43, with the exception that AmDMQA from Example 7 (1 g, 2.9mmol) was used instead of AAOA-APEA, resulting in the formation ofpolymeric dispersant comprising a polymeric group and an organicchromophore group (AmDMQA-J683).

Examples 45-47 and Comparative Examples 12-14

The following examples demonstrate improved properties of an inkjet inkcomposition of the present invention, comprising a pigment and apolymeric dispersant that comprises a polymeric group and an organicchromophore group.

Pigment dispersions were prepared using Method 2 above. Specificpigments and dispersants used for each example are shown in Table 5below.

TABLE 5 Example # Pigment Dispersant Method Particle size 45 PY 74AAOA-APEA-J683 2 0.139 (Ex 43) Comp Ex 12 PY 74 J683 2 0.1097 46 PR 122AmDMQA-J683 (Ex 44) 2 0.0925 Comp Ex 13 PR 122 J683 2 0.0799 47 PB 15:4AmDMQA-J683 (Ex 44) 2 0.0989 Comp Ex 14 PB 15:4 J683 2 0.0977

Thermal stability trials were conducted at 70° C. for three separateformulations of each example: the neat dispersion at 4% pigment, thedispersion at 4% pigment with 10% 1,2-hexanediol (1,2HD), and thedispersion at 4% pigment with 10% tetraethylene glycol monobutyl ether(TEGMBE). Particle size growth was monitored using a UPA Microtrac laserscattering equipment. A dispersion was considered stable when a particlesize increase of <20% was observed compared to the initial particle sizewhile a dispersion was considered unstable when a particle sizeincrease >20% was observed. Results for each dispersion are shown inTable 6 below.

TABLE 6 Example # Neat 10% 1,2-HD 10% TEGMBE 45 stable week 6 unstableweek 2 stable week 6 Comp Ex 12 unstable week 1 unstable week 1 unstableweek 1 46 stable week 6 unstable week 2 stable week 6 Comp Ex 13unstable week 1 unstable week 1 unstable week 1 47 stable week 6 stableweek 6 stable week 6 Comp Ex 14 unstable week 4 unstable week 6 unstableweek 6

As the results show, pigment dispersions prepared using a polymericdispersant comprising a polymeric group and an organic chromophore group(Examples 45-47) exhibited improved heat-aging stabilities (70° C.)compared to pigment dispersion comprising the same pigments and apolymeric dispersant without an organic chromophore group (ComparativeExamples 12-14). Surprisingly, this was found whether the organicchromophore group was the same as the organic chromophore group of thecolorant of the pigment (Example 45 and Example 46) or whether they weredifferent groups (Example 47).

Thus, it has surprisingly been found that improved properties resultusing a polymeric dispersant comprising an attached organic chromophoregroup. Based on this data, it would be expected that the dispersions ofExamples 45-47 could be used as an inkjet ink composition of the presentinvention.

The foregoing description of preferred embodiments of the presentinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Modifications and variationsare possible in light of the above teachings, or may be acquired frompractice of the invention. The embodiments were chosen and described inorder to explain the principles of the invention and its practicalapplication to enable one skilled in the art to utilize the invention invarious embodiments and with various modifications as are suited to theparticular use, contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto, and theirequivalents.

1. An inkjet ink composition comprising: a) a liquid vehicle; b) apigment comprising a colorant having the formula A-(B)x; and c) apolymeric dispersant comprising a polymeric group and at least one grouphaving the formula -A′-(B)y(C)z, wherein A and A′ are organicchromophore groups; B, which can be the same or different when x or y>1,is a substituent on A and N; C, which can be the same or different whenz>1, is a substituent on A′ and is different than B; x, y and z are 0,1, 2, 3 or 4; and y is less than or equal to x; and wherein A and A′ aredifferent.
 2. The inkjet ink composition of claim 1, wherein thepolymeric dispersant comprises at least one group having the formula-LG-A′-(B)y(C)z, wherein LG is a linking group.
 3. The inkjet inkcomposition of claim 1, wherein z is
 0. 4. The inkjet ink composition ofclaim 1, wherein y is
 0. 5. The inkjet ink composition of claim 1,wherein the polymeric group comprises at least one acid group or saltthereof.
 6. The inkjet ink composition of claim 1, wherein the polymericgroup is an acrylate or methacrylate polymeric group, a maleic acid ormaleic anhydride polymeric group, or a polyurethane group.
 7. The inkjetink composition of claim 1, wherein the polymeric group is astyrene-acrylic acid, a styrene-methacrylic acid, a styrene-maleicanhydride, or a styrene-maleic acid polymeric group.
 8. The inkjet inkcomposition of claim 2, wherein LG comprises a group having the formula—X-ALK1-, wherein X is O, NR, or S; R is hydrogen, a C1-C6 alkyl group,or an aryl group; and ALK1 is an alkylene group, an arylene group, anaralkylene group, or an alkarylene group having 1-18 carbons.
 9. Theinkjet ink composition of claim 8, wherein the polymeric dispersantcomprises at least one group having the formula —X-ALK1-A′-(B)y(C)z. 10.The inkjet ink composition of claim 2, wherein the polymeric dispersantcomprises at least one group having the formula —NH—CH2-A′-(B)y(C)z. 11.The inkjet ink composition of claim 2, wherein the polymeric dispersantfurther comprises at least one pendant group attached to the polymericgroup, wherein the pendant group comprises a group having the formula—X-ALK2, wherein X is O, NR, or S; R is hydrogen, a C1-C6 alkyl group,or an aryl group; and ALK2 is an alkyl group, an aryl group, an aralkylgroup, or an alkaryl group having 1-18 carbons.
 12. The inkjet inkcomposition of claim 11, wherein the pendant group has the formula—X-ALK2.
 13. The inkjet ink composition of claim 11, wherein the pendantgroup has the formula —NH-ALK2, wherein ALK2 is a C1-C12 alkyl group.14. The inkjet ink composition of claim 1, wherein the pigment comprisesa blue pigment, a black pigment, a brown pigment, a cyan pigment, agreen pigment, a white pigment, a violet pigment, a magenta pigment, ared pigment, an orange pigment, a yellow pigment, or mixtures thereof.15. The inkjet ink composition of claim 1, wherein the pigment is a cyanpigment.
 16. The inkjet ink composition of claim 15, wherein thecolorant is a phthalocyanine.
 17. The inkjet ink composition of claim15, wherein A is a phthalocyaninyl group.
 18. The inkjet ink compositionof claim 17, wherein A′ is a quinacridonylene group.
 19. An inkjet inkcomposition comprising: a) a liquid vehicle; b) a pigment comprising acolorant having the formula A-(B)x; and c) a polymeric dispersantcomprising a polymeric group and at least one organic chromophore groupcapable of interacting with the pigment; wherein A is an organicchromophore group; B, which can be the same or different when x>1, is asubstituent on A; and x is 0, 1, 2, 3, or
 4. 20. The inkjet inkcomposition of claim 19, wherein the polymeric dispersant comprises atleast one group having the formula -LG-Q, wherein LG is a linking group;and Q is the organic chromophore group capable of interacting with thepigment.